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van der Weele CM, Hospes KC, Rowe KE, Jeffery WR. Hypoxia-Sonic Hedgehog Axis as a Driver of Primitive Hematopoiesis Development and Evolution in Cavefish. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.09.598120. [PMID: 38895301 PMCID: PMC11185782 DOI: 10.1101/2024.06.09.598120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
The teleost Astyanax mexicanus consists of surface dwelling (surface fish) and cave dwelling (cavefish) forms. Cavefish have evolved in subterranean habitats characterized by reduced oxygen levels (hypoxia) and show constructive and regressive phenotypic traits controlled by increased Sonic hedgehog (Shh) signaling along the embryonic midline. The enhancement of primitive hematopoietic domains, which are formed bilaterally in the anterior and posterior lateral plate mesoderm, are responsible for the development of more larval erythrocytes in cavefish relative to surface fish. In this study, we determine the role of hypoxia and Shh signaling in the development and evolution of primitive hematopoiesis in cavefish. We show that hypoxia treatment during embryogenesis increases primitive hematopoiesis and erythrocyte development in surface fish. We also demonstrate that upregulation of Shh midline signaling by treatment with the Smoothened agonist SAG increases primitive hematopoiesis and erythrocyte development in surface fish, whereas Shh downregulation via treatment with the Smoothened inhibitor cyclopamine decreases these traits in cavefish. Together these results suggest that hematopoietic enhancement is regulated by hypoxia and the Shh signaling system. Lastly, we demonstrate that hypoxia treatment enhances expression of Shh signaling along the midline of surface fish embryos. Thus, we conclude that a hypoxia-Shh axis may drive the adaptive evolution of primitive hematopoiesis and erythrocyte development in cavefish. Highlights Hypoxia increases hematopoiesis and erythrocytes in surface fishShh upregulation increases hematopoiesis and erythrocytes in surface fishShh inhibition decreases hematopoiesis and erythrocytes in cavefishHypoxia upregulates Shh along the embryonic midline in surface fish.
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Cobham AE, Rohner N. Unraveling stress resilience: Insights from adaptations to extreme environments by Astyanax mexicanus cavefish. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART B, MOLECULAR AND DEVELOPMENTAL EVOLUTION 2024; 342:178-188. [PMID: 38247307 DOI: 10.1002/jez.b.23238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 12/26/2023] [Accepted: 01/02/2024] [Indexed: 01/23/2024]
Abstract
Extreme environmental conditions have profound impacts on shaping the evolutionary trajectory of organisms. Exposure to these conditions elicits stress responses, that can trigger phenotypic changes in novel directions. The Mexican Tetra, Astyanax mexicanus, is an excellent model for understanding evolutionary mechanisms in response to extreme or new environments. This fish species consists of two morphs; the classical surface-dwelling fish and the blind cave-dwellers that inhabit dark and biodiversity-reduced ecosystems. In this review, we explore the specific stressors present in cave environments and examine the diverse adaptive strategies employed by cave populations to not only survive but thrive as successful colonizers. By analyzing the evolutionary responses of A. mexicanus, we gain valuable insights into the genetic, physiological, and behavioral adaptations that enable organisms to flourish under challenging environmental conditions.
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Affiliation(s)
- Ansa E Cobham
- Stowers Institute for Medical Research, Missouri, Kansas City, USA
| | - Nicolas Rohner
- Stowers Institute for Medical Research, Missouri, Kansas City, USA
- Department of Cell Biology & Physiology, University of Kansas Medical Center, Kansas City, Missouri, USA
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Jiménez AG, Nash-Braun E, Meyers JR. White epaxial muscle aerobic and anaerobic potential and muscle fiber structure in surface and cave morphotypes of the Mexican cavefish (Astyanax mexicanus). JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2023; 339:861-868. [PMID: 37493010 DOI: 10.1002/jez.2736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 07/07/2023] [Accepted: 07/10/2023] [Indexed: 07/27/2023]
Abstract
Proper muscle function and muscle fiber structures that match the environmental demands of organisms are imperative to their success in any ecosystem. The Mexican cavefish, Astyanax mexicanus, has two morphotypes: an obligate cave-dwelling form that lives in thermally insulated caves and an O2 poor environment, and a surface form that lives in a more thermally variable, but O2 rich river environment. As environment can determine physiological adaptations, it is of interest to compare the aerobic and anaerobic metabolic profiles of white muscle metabolism in both morphotypes of this species, as well as their muscle structures. Here, we used white muscle of both morphotypes of the Mexican cavefish to determine citrate synthase (CS) activity as a measure of aerobic potential, and lactate concentration as a measure of anaerobic potential at three different chronic acclimation temperatures (14°C, 25°C, and 31°C). By examining aerobic and anaerobic potential in both morphs, we sought to link environmental thermal flexibility to muscle metabolism. We found that the surface morphotype had higher CS activity and lower lactate concentration, suggesting an overall more efficient usage of aerobic metabolism; whereas the cave morphotype showed lower CS activity and higher lactate concentration, suggesting a stronger reliance on anaerobic pathways. We also measured white muscle histological variables that have been previously linked to whole-animal metabolism: fiber diameter, number of nuclei per mm of fiber and myonuclear domain (MND) of both morphotypes at 25°C to examine cell-level differences in muscle morphology. However, we found no differences in fiber diameter, number of nuclei per mm of fiber or MND between the two morphotypes. Thus, although the cellular morphology is similar in these species, the environmental differences in the evolution of the two morphs has led to differences in their metabolic profiles.
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Affiliation(s)
| | - Evan Nash-Braun
- Department of Biology, Colgate University, Hamilton, New York, USA
| | - Jason R Meyers
- Department of Biology, Colgate University, Hamilton, New York, USA
- Neuroscience Program, Colgate University, Hamilton, New York, USA
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Paz A, Holt KJ, Clarke A, Aviles A, Abraham B, Keene AC, Duboué ER, Fily Y, Kowalko JE. Changes in local interaction rules during ontogeny underlie the evolution of collective behavior. iScience 2023; 26:107431. [PMID: 37636065 PMCID: PMC10448030 DOI: 10.1016/j.isci.2023.107431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 06/17/2023] [Accepted: 07/17/2023] [Indexed: 08/29/2023] Open
Abstract
Collective motion emerges from individual interactions which produce group-wide patterns in behavior. While adaptive changes to collective motion are observed across animal species, how local interactions change when these collective behaviors evolve is poorly understood. Here, we use the Mexican tetra, Astyanax mexicanus, which exists as a schooling surface form and a non-schooling cave form, to study differences in how fish alter their swimming in response to neighbors across ontogeny and between evolutionarily diverged populations. We find that surface fish undergo a transition to schooling mediated by changes in the way fish modulate speed and turning relative to neighbors. This transition begins with the tendency to align to neighbors emerging by 28 days post-fertilization and ends with the emergence of robust attraction by 70 days post-fertilization. Cavefish exhibit neither alignment nor attraction at any stage of development. These results reveal how evolution alters local interactions to produce striking differences in collective behavior.
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Affiliation(s)
- Alexandra Paz
- Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Karla J. Holt
- Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Anik Clarke
- Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Ari Aviles
- Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Briana Abraham
- Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Alex C. Keene
- Department of Biology, Texas A&M, College Station, TX 77840, USA
| | - Erik R. Duboué
- Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Yaouen Fily
- Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Johanna E. Kowalko
- Department of Biological Sciences, Lehigh University, Bethlehem, PA 18015, USA
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Jiménez AG, Nash-Braun E, Meyers JR. Chronic Thermal Acclimation Effects on Critical Thermal Maxima (CT max) and Oxidative Stress Differences in White Epaxial Muscle between Surface and Cave Morphotypes of the Mexican Cavefish ( Astyanax mexicanus). Physiol Biochem Zool 2023; 96:369-377. [PMID: 37713718 DOI: 10.1086/726338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/17/2023]
Abstract
AbstractIn the face of increasing environmental temperatures, operative differences between mitochondrial function and whole-animal phenotypic response to the environment are underrepresented in research, especially in subtemperate ectothermic vertebrates. A novel approach to exploring this connection is to examine model species that are genetically similar but that have different whole-animal phenotypes, each of which inhabits different environments. The blind Mexican cavefish (Astyanax mexicanus) has the following two morphotypes: a surface form found in aboveground rivers and an obligate cave-dwelling form. Each morphotype inhabits vastly different thermal and oxygen environments. Whole-animal and mitochondrial responses to thermal acclimation and oxidative stress, with respect to increasing temperatures, have not been previously determined in either morphotype of this species. Here, we chronically acclimated both morphotypes to three temperatures (14°C, 25°C, and 31°C) to establish potential for acclimation and critical thermal maxima (CTmax) for each morphotype of this species. After measuring CTmax in six cohorts, we additionally measured enzymatic antioxidant capacity (catalase, superoxide dismutase, and glutathione peroxidase activities), peroxyl scavenging capacity, and lipid peroxidation damage in white epaxial muscle for each individual. We found a significant effect of acclimation temperature on CTmax (F = 29.57 , P < 0.001 ) but no effect of morphotype on CTmax (F = 2.092 , P = 0.162 ). Additionally, we found that morphotype had a significant effect on glutathione peroxidase activity, with the surface morphotype having increased glutathione peroxidase activity compared with the cave morphotype (F = 6.270 , P = 0.020 ). No other oxidative stress variable demonstrated significant differences. Increases in CTmax with chronic thermal acclimation to higher temperatures suggests that there is some degree of phenotypic plasticity in this species that nominally occupies thermally stable environments. The decreased glutathione peroxidase activity in the cave morphotype may be related to decreased environmental oxygen concentration and decreased metabolic rate in this environmentally constrained morphotype compared to in its surface-living counterparts.
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Moran RL, Richards EJ, Ornelas-García CP, Gross JB, Donny A, Wiese J, Keene AC, Kowalko JE, Rohner N, McGaugh SE. Selection-driven trait loss in independently evolved cavefish populations. Nat Commun 2023; 14:2557. [PMID: 37137902 PMCID: PMC10156726 DOI: 10.1038/s41467-023-37909-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 04/03/2023] [Indexed: 05/05/2023] Open
Abstract
Laboratory studies have demonstrated that a single phenotype can be produced by many different genotypes; however, in natural systems, it is frequently found that phenotypic convergence is due to parallel genetic changes. This suggests a substantial role for constraint and determinism in evolution and indicates that certain mutations are more likely to contribute to phenotypic evolution. Here we use whole genome resequencing in the Mexican tetra, Astyanax mexicanus, to investigate how selection has shaped the repeated evolution of both trait loss and enhancement across independent cavefish lineages. We show that selection on standing genetic variation and de novo mutations both contribute substantially to repeated adaptation. Our findings provide empirical support for the hypothesis that genes with larger mutational targets are more likely to be the substrate of repeated evolution and indicate that features of the cave environment may impact the rate at which mutations occur.
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Affiliation(s)
- Rachel L Moran
- Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, MN, USA.
- Department of Biology, Texas A&M University, College Station, TX, USA.
| | - Emilie J Richards
- Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, MN, USA
| | - Claudia Patricia Ornelas-García
- Colección Nacional de Peces, Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, Tercer Circuito Exterior S/N. CP 04510, D. F. México, México City, México
| | - Joshua B Gross
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, USA
| | - Alexandra Donny
- Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, MN, USA
| | - Jonathan Wiese
- Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, MN, USA
| | - Alex C Keene
- Department of Biology, Texas A&M University, College Station, TX, USA
| | - Johanna E Kowalko
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, USA
| | - Nicolas Rohner
- Stowers Institute for Medical Research, Kansas City, MO, USA
- Department of Molecular & Integrative Physiology, KU Medical Center, Kansas City, KS, USA
| | - Suzanne E McGaugh
- Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, MN, USA
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Paz A, Holt KJ, Clarke A, Aviles A, Abraham B, Keene AC, Duboué ER, Fily Y, Kowalko JE. Changes in local interaction rules during ontogeny underlie the evolution of collective behavior. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.28.534467. [PMID: 37034671 PMCID: PMC10081253 DOI: 10.1101/2023.03.28.534467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Collective motion emerges from individual interactions which produce groupwide patterns in behavior. While adaptive changes to collective motion are observed across animal species, how local interactions change when these collective behaviors evolve is poorly understood. Here, we use the Mexican tetra, A. mexicanus, which exists as a schooling surface form and a non-schooling cave form, to study differences in how fish alter their swimming in response to neighbors across ontogeny and between evolutionarily diverged populations. We find that surface fish undergo a transition to schooling during development that occurs through increases in inter-individual alignment and attraction mediated by changes in the way fish modulate speed and turning relative to neighbors. Cavefish, which have evolved loss of schooling, exhibit neither of these schooling-promoting interactions at any stage of development. These results reveal how evolution alters local interaction rules to produce striking differences in collective behavior.
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Affiliation(s)
- Alexandra Paz
- Wilkes Honors College, Florida Atlantic University, Jupiter FL
| | - Karla J. Holt
- Wilkes Honors College, Florida Atlantic University, Jupiter FL
| | - Anik Clarke
- Wilkes Honors College, Florida Atlantic University, Jupiter FL
| | - Ari Aviles
- Wilkes Honors College, Florida Atlantic University, Jupiter FL
| | - Briana Abraham
- Wilkes Honors College, Florida Atlantic University, Jupiter FL
| | | | - Erik R. Duboué
- Wilkes Honors College, Florida Atlantic University, Jupiter FL
| | - Yaouen Fily
- Wilkes Honors College, Florida Atlantic University, Jupiter FL
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Lunghi E, Bilandžija H. Longevity in Cave Animals. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.874123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
An extraordinary longevity has been observed in some cave species, and this raised the hypothesis that a longer lifespan may be considered one of the characteristic traits of these animals. However, only a few cave species have been studied thus far, and a firm conclusion remains to be drawn. Here we review the available knowledge on the longevity of subterranean species, point out the limitations of previous studies, and provide suggestions for future studies to answer important questions regarding the longevity in cave animals, its adaptive value and the related promoting factors. We also argue that studying the longevity in cave animals will contribute to the field of aging, especially to understanding the evolution of this phenomenon.
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Mar-Silva AF, Arroyave J, Díaz-Jaimes P. The complete mitochondrial genome of the Mexican-endemic cavefish Ophisternon infernale (Synbranchiformes, Synbranchidae): insights on patterns of selection and implications for synbranchiform phylogenetics. Zookeys 2022; 1089:1-23. [PMID: 35586600 PMCID: PMC8933388 DOI: 10.3897/zookeys.1089.78182] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 01/26/2022] [Indexed: 12/01/2022] Open
Abstract
Ophisternoninfernale is one of the 200+ troglobitic fish species worldwide, and one of the two cave-dwelling fishes endemic to the karstic aquifer of the Yucatán Peninsula, Mexico. Because of its elusive nature and the relative inaccessibility of its habitat, there is virtually no genetic information on this enigmatic fish. Herein we report the complete mitochondrial genome of O.infernale, which overall exhibits a configuration comparable to that of other synbranchiforms as well as of more distantly related teleosts. The KA/KS ratio indicates that most mtDNA PCGs in synbranchiforms have evolved under strong purifying selection, preventing major structural and functional protein changes. The few instances of PCGs under positive selection might be related to adaptation to decreased oxygen availability. Phylogenetic analysis of mtDNA comparative data from synbranchiforms and closely related taxa (including the indostomid Indostomusparadoxus) corroborate the notion that indostomids are more closely related to synbranchiforms than to gasterosteoids, but without rendering the former paraphyletic. Our phylogenetic results also suggest that New World species of Ophisternon might be more closely related to Synbranchus than to the remaining Ophisternon species. This novel phylogenetic hypothesis, however, should be further tested in the context of a comprehensive systematic study of the group.
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van der Weele CM, Jeffery WR. Cavefish cope with environmental hypoxia by developing more erythrocytes and overexpression of hypoxia-inducible genes. eLife 2022; 11:69109. [PMID: 34984980 PMCID: PMC8765751 DOI: 10.7554/elife.69109] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 12/31/2021] [Indexed: 12/24/2022] Open
Abstract
Dark caves lacking primary productivity can expose subterranean animals to hypoxia. We used the surface-dwelling (surface fish) and cave-dwelling (cavefish) morphs of Astyanax mexicanus as a model for understanding the mechanisms of hypoxia tolerance in the cave environment. Primitive hematopoiesis, which is restricted to the posterior lateral mesoderm in other teleosts, also occurs in the anterior lateral mesoderm in Astyanax, potentially pre-adapting surface fish for hypoxic cave colonization. Cavefish have enlarged both hematopoietic domains and develop more erythrocytes than surface fish, which are required for normal development in both morphs. Laboratory-induced hypoxia suppresses growth in surface fish but not in cavefish. Both morphs respond to hypoxia by overexpressing hypoxia-inducible factor 1 (hif1) pathway genes, and some hif1 genes are constitutively upregulated in normoxic cavefish to similar levels as in hypoxic surface fish. We conclude that cavefish cope with hypoxia by increasing erythrocyte development and constitutive hif1 gene overexpression.
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Affiliation(s)
| | - William R Jeffery
- Department of Biology, University of Maryland, College Park, United States
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